1. Field of Invention
The present invention relates generally to data communication networks and devices, and relates more particularly to the discovery of a maximum transmission unit (MTU) size in a network path of a data communication network.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
In a data communication network, when one Internet Protocol (IP) host has a large amount of data to send to another host, the data is transmitted as a series of IP datagrams or packets. It is often preferable that these datagrams be of a largest size that does not require fragmentation anywhere along the path from the source to the destination. This datagram size may be referred to as the maximum transmission unit (MTU) for the path and may be referred to as the path MTU or PMTU. The PMTU thus is the minimum of the MTUs of each hop in the path.
Conventional techniques for path MTU discovery may involve first setting the “do not fragment” (DF) flag on a packet sent by a source node. If a router has a communication interface with a next hop MTU size smaller than the packet size, an Internet Control Message Protocol (ICMP) error message is returned along with the smaller next hop MTU size and the packet is dropped. Upon receiving the ICMP error message, the source node may resend a smaller packet according to the MTU size recorded in the ICMP error message. The resending process may be repeated until the packet is received by the intended destination node. Upon receiving the packet, the destination node may send an acknowledgement message to confirm the MTU of the path. On a path with a plurality of nodes and various MTU sizes, multiple rounds of packet transmission may be necessary to determine the path MTU. Thus the conventional techniques for path MTU discovery are inefficient.
Accordingly, there is need for an optimized path MTU discovery system and method to reduce the number of packets and the effective time in determining the MTU of a path.